package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.*;

/**
 * @author: yp
 * @Description:
 * @creat:2022/10/27/16:41
 */
@Slf4j
@Component
public class CacheClient {
    private final StringRedisTemplate stringRedisTemplate;

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit unit ){
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,unit);
    }
    public void setWithLogicalExpire(
            String key, Object value, Long time, TimeUnit unit ){
        //设置逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        //写入redis
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }

    public <R,ID> R queryWithPassThrough(
            String KeyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback,Long time, TimeUnit unit
    ){
        //1.根据id查询redis中存在
        String key = KeyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);

//       2. 存在 就返回
        if (StrUtil.isNotBlank(json)){
            return JSONUtil.toBean(json, type);
        }

//        判断是否是空值
        if (json != null){
            return null;
        }

//      3.  不存在 去数据库中查询
        R r = dbFallback.apply(id);
//        4.数据库中不存在，返回404
        if (r == null){
//            将空值返回redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            //店铺不存在
            return null;
        }

//        5.数据库中存在 ，先写入到redis中
        this.set(key,r,time,unit);
//      6.  返回商铺信息
        return r;
    }
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    public <R,ID> R queryWithLogicalExpire(
            String keyPrefix,ID id,Class<R> type,Function<ID,R> dbFallback
            ,Long time, TimeUnit unit
    ){
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
//       2. 不存在 就返回null
        if (StrUtil.isBlank(json)){
            return null;
        }
        //3.命中 ,先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        R r = JSONUtil.toBean((JSONObject) redisData.getData(),type);
        LocalDateTime expireTime = redisData.getExpireTime();
        //4. 判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())){
            //5.1.未过期,返回店铺信息
            return r;
        }
        //5.2.1.已过期
        //5.2.2 获取互斥锁
        String lockKey = LOCK_SHOP_KEY+id;
        boolean isLock = tryLock(lockKey);
        //5.2.3 判断互斥锁是否获取
        if (isLock){
            // TODO5.2.3.1 获取 开启独立线程实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() ->{
                try {
                    //查询数据库
                    R r1 = dbFallback.apply(id);
                    //写入redis
                    this.setWithLogicalExpire(key,r1,time,unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {

                    //释放锁
                    unlock(lockKey);
                }
            });

        }

        return r;
    }

    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }



}
